An existing continuously variable transmission for a vehicle including a metal V-belt (or chain) will now be described with reference to FIG. 96.
It is noted that throughout the detailed description and the drawings some parts are designated by reference numerals appended with characters, such as “L”, “R”, “D” and “F”, in which “L” means “left”, “R” means “right”, “D” means driving, and “F” means “follower (driven)”.
For example, a left driving adjustment sun gear is designated by a reference numeral appended with LD, while a right driven adjustment sun gear is designated by a reference numeral appended with RF. A left direction or a right direction corresponds to a left side or a right side when viewing in the drawing.
A cone portion of a driving pulley is connected to a cone portion of a driven pulley by the metal V belt (or chain). The continuously variable transmission mainly includes a torque converter 1, an input shaft 2, a metal belt or chain 3, pulleys 4RD, 4LD, 4RF and 4LF, and an output shaft 5.
With the construction of the conventional continuously variable transmission, when the left driving pulley 4LD is axially moved in a left direction and the right driven pulley 4RF is axially moved in a left direction, a radius of the belt in the driving unit is reduced, while a radius of the belt in the driven unit is increased. On the contrary, when the left driving pulley 4LD is axially moved in a right direction and the right driven pulley 4RF is axially moved in a right direction, a radius of the belt in the driving unit is increased, while a radius of the belt in the driven unit is reduced. Therefore, the continuously variable transmission is a device to change a speed by adjusting the left driving pulley 4LD and the right driven pulley 4RF.
According to the conventional continuously variable transmission, however, a contact surface between the metal belt or chain 3 and the cone portion of the pulley is worn or slip to decrease a transmitting efficiency. Also, since it is limitedly used for a vehicle of low capacity, the continuously variable transmission is inefficient in case of a transmission device requiring high capacity. In addition, many costs are required to maintain a frictional force and study abrasion resistance material.